The present invention relates to a method of forming a mold for use in casting steel products, and, more particularly, to a method of forming a mold for use in the manufacture of steel castings such as holsters, sideframes, couplers, yokes, draft sills and related components for railway freight car trucks.
Traditionally, such steel castings for railway freight car trucks are comprised of cast steel components that are unitary in structure. Such steel castings are typically comprised of steel that is poured into green sand molds. Such green sand molds are typically formed by the injection and compaction of green sand, of which clay is the binder element, by a slinger into a cope or drag pattern placed in a flask. Alternately, such flask can be placed over the cope or drag pattern and green sand is poured to fill the flask, whereupon the flask is jolted to set the green sand cope or drag pattern in the flask.
The formation of the cope and drag halves of the mold for use in forming such cast steel components has a major disadvantage in that an assembled bolster mold comprised of a bottom or drag half and a top or cope half, comprises over 4,000 pounds of green sand, not including the cores placed into the drag half before the cope half is placed on top to form a complete mold for pouring. Such large quantity of green sand must be reclaimed after the molten steel is poured into the bolster mold before the sand can be reused to form another bolster mold. Similar amounts of sand are required in the casting of a sideframe or a draft sill, with lesser, but still substantial, amounts of sand for casting a coupler body or a coupler yoke. Such processing of such large amounts of sand is both time consuming and expensive.
Accordingly, it is an object of the present invention to provide a more efficient method of forming a mold for use in the casting of a steel bolster, sideframe, coupler, yoke, draft sill or other cast steel component of a railway freight car truck.
Another object of the present invention is to provide an inherently more dimensionally accurate bolster, sideframe, coupler, yoke, draft sill or other cast steel component of a railway freight car truck by the use of a permanent flask lined with a resin coated sand, formed to a pattern.